Pinch-base electric lamp with transversely arranged supply wires

ABSTRACT

A pinch-base lamp and method of making same where foils are sealed in the pinch, and secured to each foil are one end of a pole wire oriented generally parallel to the lamp axis and one end of a supply wire oriented at a right-angle to the pole wire. When the lamp is mounted the laterally extending supply wires are subjected to torsional instead of bending stress, thereby reducing the likelihood of fracturing the pinch, and the base of the pinch, being free of supply wires, may be ground to provide an accurate reference surface from the filament.

United States Patent 2 ,491,237 12/1949 Way Inventors Riksterus Auguste Johannes Maria Meijer P1NCH-BASE ELECTRIC LAMP WITH TRANSVERSELY ARRANGED'SUPPLY WIRES 5 Claims, 5 Drawing Figs.

us. (I 313/318, 313/331 Ill. (I H01] 5/48 FieldolSeareh 313/318, 331,286,290, 266

m Cited UNITED STATES PATENTS Primary Examiner-Darrid Schonberg Assistant Examiner-Toby l-i. Kusmer Attorney-Frank R. Trifari ABSTRACT: A pinch-base lamp and method of making same where foils are sealed in the pinch, and secured to each foil are one end of a pole wire oriented generally parallel to the lamp axis and one end of a supply wire oriented at a right-angle to the pole wire. When the lamp is mounted the laterally extending supply wires are subjected to torsional instead of bending stress, thereby reducing the likelihood of fracturing the pinch, and the base of the pinch, being free of supply wires, may be ground to provide an accurate reference surface from the filament.

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INVIENTORS R. A. JOH A N N E 5 MARIA MEIJER JAN 6. PENNEKAMP B Y PINCH-BASE ELECTRIC LAMP WITI-I TRANSVERSELY ARRANGED SUPPLY WIRES Known in the prior art are electric lamps, having at one end a gastight flat pinch, and one or more metal foils sealed in the pinch; connected to each foil is the end of a current supply wire projecting outside the lamp and the end of a pole wire projecting inside the lamp space.

In these lamps it is common practice to lead the current supply wires projecting outside the lamp to the exterior through the narrow limiting of the lamp pinch remote from the lamp space. As a result of this a comparatively large space must be available for such a lamp to be mounted, for example, in a car, headlight viewed in the longitudinal direction of the saidlamp. It is the object of the invention to mitigate this drawback.

According to the present invention, the lamp of the type mentioned in the preamble is characterized in that the current supply wire and the pole wire secured to the same foil and incorporated in a pinch are arranged at right-angles to each other, and the current supply wire leaves the pinch through one of the lateral narrow boundary surfaces of said pinch.

In addition to the advantage of a short length of the lamp a further advantage is obtained. When the lamp is mounted in a lamp holder which is subject to vibrations, the parts of the current supply wires emerging from the lateral narrow boundaries of said pinch are torsionally stressed in the lamp according to the invention. It has been found in practice that in the lamp according to the invention, which is comparatively short, the possibility of fracture of the pinch by the forces exerted thereon by the current supply wires in the case described, is less than when said current supply wires are stressed for bending, as is the case in the known longer lamp.

A particularly short structural length of the lamp according to the invention is obtained when it is constructed so that the current supply wires which leave a pinch through one of its narrow lateral boundaries extend outside the lamp fully laterally of the pinch.

In a further embodiment of the lamp according to the invention, the boundary of the pinch remote from the space of the envelope has a ground surface. Actually, in the lamp according to the invention, said boundary surface is free from current supply wires. Therefore the pinch can be subjected to the grinding operation atthe area of said boundary surface, so that the said surface may serve as a reference surface for aligning the lamp in an associated optical system. In this manner a finished lamp can be given a prescribed light center length.

In a further embodiment of the lamp according to the invention, the currentsupply wires projecting from the lateral narrow boundary surfaces of the pinch consist of silicated molybdenum. As a result of this the laterally projecting wires which are exposed to the high temperatures of burner flames during the fonnation of the pinch, are resistent to oxidation.

An advantageous method of manufacturing a lamp according to the invention is characterized in that one or a few combinations of foils having each two wires secured thereto at right-angles to each other are arranged in a jig while using a third wire to be threaded in said jig and secured to such a foil in such manner that the first and the second of the said wires secured to such a foil extend according to and at right-angles to, respectively, the longitudinal direction of the lamp to be manufactured, an envelope consisting of glass or quartz glass being then placed over said assembly after which the envelope is heated in the proximity of the foil and is squeezed in a gastight manner around the foils, a part of the current supply wire extending at right-angles to the foil becoming located outside one of the lateral narrow boundaries of the pinch. In this method, the above-mentioned third wire secured to each of the foils, only serves to fix the combinations of said foil with the two wires secured thereto at right-angles to each other during the manufacture of the pinch in a jig.

The lamp according to the invention may be constructed with one or with two seals as described, in the latter case on either end of the lamp. The invention may furthermore be applied to electric filament lamps in which a filament is stretched between the pole wires or to electric discharge lamps in which the pole wires support the electrodes necessary for the discharge or serve as electrodes themselves.

In order that the invention may be readily carried into effect, it will now be described in greater detail, by way of example with reference to the accompanying drawings, in which:

FIG. I is a first embodiment of the lamp according to the invention. In this figure it is also shown in what manner a prescribed light center length can be given to such a lamp.

FIGS. 2, 3 and 4 diagrammatically show how the lamp according to the invention can be manufactured.

FIG. 5 shows a lamp in which the seal is manufactured by means of the method shown in FIGS. 2, 3 and 4.

The lamp shown in FIG. 1 comprises an envelope 10 consisting of quartz glass, the lower end of which is deformed to a flat pinch ll. Said pinch comprises two metal foils l2 and 13, respectively. In directions extending at right-angles to each other pole wires 14 and 15, respectively, and current supply wires 16 and 17, respectively, are secured to each of the said foils. The pole wires 14 and 15 support a filament 18. The envelope 10 comprises a sealed exhaust tube 19.

As shown in FIG. 1 the current supply wires 16 and 17 project from the lateral narrow boundary surfaces 20 and 21, respectively, of the flat pinch. As a result of this a short structural length of the lamp is obtained.

When the current supply wires 16 and 17 are incorporated in the diagrammatically shown contacts 22 and 23 of a lampholder (not shown), the current supply wires 16 and 17, upon vibration of the lampholder, will mainly be torsionally stressed which, in combination with a short lamp length, results in less chance of fracture of the pinch 11 than when said current supply wires would project through the end 25 remote from the lamp space 24 of the pinch 11 of a comparatively long lamp. I I

In the lamp according to the invention, the said end 25 of the pinch 11 is free from current supply wires. As a result of this the advantage is obtained that the light center length of the lamp can be adapted to the requirements to be imposed.

In the lamp shown the distance between the filament I8 and the end 25 of the pinch has a value a. When the light center length prescribed for said lamp must have a value b, this requirement can be met in the lamp construction shown. This may be effected by grinding away the shaded lower portion 26 of the pinch 11 so that the end of the pinch becomes situated at 27 and the requirement regarding the light center length has been met.

A method by means of which the lamp shown in FIG. 1 can be manufactured will now be described with reference to FIGS. 2, 3 and 4.

In this method, supporting wires 43 and 44 are placed in two apertures 40 and 41, in a jig 42, which supporting wires are secured to metal foils 45 and 46. Said metal foils 45 and 46 are similar to the metal foils 12 and 13 shown in FIG. I. In addition to the just mentioned supporting wires 43 and 44, the current supply wires 47 and 48, respectively, and the pole wires 49 and 50, respectively, are secured to said metal foils 45 and 46. A filament 51 is stretched between the pole wires 49 and 50.

A tubular envelope 52 consisting of quartz glass is then placed around said assembly, of which envelope only the lower side is shown. At its lower side said envelope comprises two slots 53 and 54, respectively, so that it can become to engage the upper side of the jig 42. The current supply wires 47 and 48 actually project through the slots 53 and 54.

As is shown particularly in FIG. 4, the jaws 55 and 56 of a pair of pincers are situated on either side of the envelope 52. These jaws have flat surfaces 57 and 58, respectively, comprising recesses 59 and 60, respectively. After the lower part of the envelope 52 has been heated to a sufficiently high temperature, for example over the region having length denoted by c, the jaws 55 and 56 of the pincers are moved towards each other and the pinch 61 of the lamp shown in FIG. 5 is formed. Due to the presence of the recesses 59 and 60 in the flat surfaces 57 and 58 of the jaws, the current supply wires 47 and 48 projecting laterally from the pinch remain free from the surfaces of the pincers. After the jaws have been moved outwards again, the product shown in FIG. 5 can be taken out of the jig. The supporting wires 43 and 44 project from the end 64 of the pinch 61 remote from the lamp space 63. These ends which do not perform any function for operating the lamp can be cut. Furthermore, if desirable, in the manner as shown in FIG. 1, the light center length of the lamp can be adjusted by grinding away the pinch 61 at its boundary surface 64.

What is claimed is:

1. An electric lamp comprising a sealed glass bulb having a central axis and a pinched-base defining a bottom end and sides, at least two-spaced foils sealed in the pinch, at least two pole wires within the bulb, each being generally parallel with said axis and each having one end secured to one foil, a filament disposed within the bulb, the ends of the filament bridging the remote ends of the pole wires, at least two current supply wires, each having one end secured to one foil in the pinch and its remote end extending through the sides of the pinch generally transverse to the pole wires.

2. An electric lamp as defined in claim 9 wherein the supply wires are oriented at approximately with respect to said pole wires.

3. A lamp as defined in claim 10 wherein the base part of said pinch isground, defining a reference surface accurately spaced from the filament.

4. A lamp as defined in claim 10 further comprising two support wires, each having one end secured to one foil within a pinch and each having its remote end extending through the bottom of the pinch.

5. An electric lamp as defined in claim 10 wherein the current supply wires comprise silicated molybdenum.

3 3 33 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 5L7 797 Dated m b 2 121] Inventor(s) R.A.J.M. MEIJER ET AL It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE CLAIMS Claim 2, line 1, cancel "claim 9" and insert claim l;

Claim 3, line 1, cancel "claim 10" and insert claim 2--;

Claim 4, line 1, cancel "claim 10" and insert claim 2--;

Claim 5, line 1, cancel "claim 10" and insert claim 2-.

Signed and sealed thie 31st day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTISGHALK Attesting Officer Commissioner of Patents 

1. An electric lamp comprising a sealed glass bulb having a central axis and a pinched-base defining a bottom end and sides, at least two-spaced foils sealed in the pinch, at least two pole wires within the bulb, each being generally parallel with said axis and each having one end secured to one foil, a filament disposed within the bulb, the ends of the filament bridging the remote ends of the pole wires, at least two current supply wires, each having one end secured to one foil in the pinch and its remote end extending through the sides of the pinch generally transverse to the pole wires.
 2. An electric lamp as defined in claim 9 wherein the supply wires are oriented at approximately 90* with respect to said pole wires.
 3. A lamp as defined in claim 10 wherein the base part of said pinch is ground, defining a reference surface accurately spaced from the filament.
 4. A lamp as defined in claim 10 further comprising two support wires, each having one end secured to one foil within a pinch and each having its remote end extending through the bottom of the pinch.
 5. An electric lamp as defined in claim 10 wherein the current supply wires comprise silicated molybdenum. 